1. Field of the Invention
The present invention relates to a bumper absorber that is provided on an automobile between a bumper reinforcement and a bumper fascia, and a manufacturing method for the same.
2. Description of the Related Art
Bumpers that provide a shock absorbing capability are provided at the front and rear ends of an automobile in order to protect the vehicle body and in order to reduce the load that is applied to the legs of a pedestrian when the pedestrian is involved in an accident with a vehicle. A bumper absorber is provided between the bumper reinforcement and the bumper fascia.
Patent Document 1 (Japanese Patent Application Publication No. JP-A-2004-345423) and Patent Document 2 (Japanese Patent Application Publication No. JP-A-2004-345425) disclose an impact energy absorbing apparatus for a vehicle bumper that is provided with a compression energy absorbing material, a buckling energy absorbing material that includes plate-shaped members, and a plurality of columnar linking members that are disposed with spaces therebetween. Paragraph 0008 and FIG. 6 in Patent Document 1 disclose that in the compression energy absorbing material, a tendency is exhibited in which the acting shock force becomes larger as the displacement thereof becomes larger, and in the buckling energy absorbing material, a tendency is exhibited in which, during the initial stage in which a shock force is acting, the acting shock force rapidly becomes large and approaches a peak value, and subsequently, the shock force rapidly decreases. In addition, by combining the impact energy absorption characteristics of the compression energy absorbing material and the impact energy absorbing characteristics of the buckling energy absorbing material, over the entire impact energy absorbing interval during which the impact energy is absorbed by both impact absorbing materials, the shock force thereon is maintained at a target value that enables the protecting of a pedestrian, and the maximum absorption of the impact energy is enabled while the protective capacity of the pedestrian is ensured.
Paragraph 0012 of Patent Document 1 discloses that, at the position at which the linking members are provided, the compression energy absorbing material does not readily undergo compression deformation by an amount equivalent to the thickness of the linking members in the front-back direction of the vehicle body, but because there are no obstructions between the linking members, substantially the whole width of the compression energy absorbing material undergoes compression deformation in the front-back direction of the vehicle body, and the impact energy can be efficiently absorbed. This means that a plurality of columnar linking members must be provided, and that a space must be provided between the linking members.
Patent Document 3 (Japanese Patent Application Publication No. JP-A-2004-345424) discloses an impact energy absorbing apparatus for a vehicle bumper that is provided with a compression energy absorbing material, a buckling energy absorbing material that consists of plate-shaped members, and a front fixed supporting member that is provided so as to project on the inner surface of the bumper fascia and to support the front end portion of both energy absorbing materials. The front fixed supporting member is integrally formed with the bumper fascia. Specifically, when viewing the impact energy absorbing apparatus from the front side after removing the bumper fascia, a large opening is formed between the compression energy absorbing material and the buckling energy absorbing material.
In the technology that is disclosed in Patent Documents 1 and 2, because the front side of both energy absorbing materials have large openings, it can be anticipated that the shock absorbing capacity will fluctuate due to the orientation of the impact surface of the impacted object that has impacted the bumper fascia. Specifically, in the case in which the impact surface of the impacted object that has impacted the bumper fascia is not perpendicular to the upper and lower surfaces of the compression energy absorbing material and the upper and lower surfaces of the buckling energy absorbing material, because a large portion of the front sides of both energy absorbing materials is open, the compression energy absorbing material and the buckling energy absorbing material collapse either upward or downward in the same direction, and it can be anticipated that the impact absorbing capacity will thereby be reduced.
In the technology that is disclosed in Patent Document 3, the structure that supports the front end portions of both energy absorbing materials must be formed on the bumper fascia, and thus the structure of the bumper fascia becomes complicated.